The present invention relates to tilting deck vehicles of a type which are especially suited for transporting heavy equipment such as compressors, generators, back-hoes, fork-lifts and the like, as well as for moving disabled automobiles and small trucks. A vehicle in accordance with this invention can be in the form of a trailer intended to be used with a separate tractor or it can be in the form of a truck having its own prime mover or motive power source.
The cost in this day and age of custom building a tilting deck truck or vehicle would be so high as to be totally unfeasible. For this reason such vehicles have been and still are generally manufactured by modifying existing production model fixed deck vehicles. For many years, it has been customary to effect such modification by mounting a tipping or tilting deck on top of the existing chassis or frame of such a commercially available vehicle. This known procedure presents the problem that the tilting deck is relatively high above the road surface. Consequently, it is difficult to effect the modification in such a way that the rear end of the deck can be fully lowered onto the ground surface without resorting to an excessive and unpractical tilt or loading angle. This problem can, of course, be avoided by extending the deck of the vehicle rearwardly but then difficulties arise with respect to weight distribution and stability as well as with respect to the ease with which the vehicle can be driven, a long rearward extension being a very serious problem under regular driving conditions.
In an attempt to avoid these problems at least partially, it has previously been proposed to provide the necessary pivot means, such as hinges, in the side rails of the actual chassis or frame of the existing vehicle and then to mount the tilting deck on the rearward section of the divided chassis so that such deck extends forwardly over the forward section of the chassis.
In the case of trucks, such division of the existing frame or chassis presents a further problem; when the rear section of the chassis of such a modified vehicle is moved into its inclined position, the rear axle of the vehicle moves in the forward direction. Since the combined universal-slip joint provided in the main drive transmission shaft of a conventional truck is generally adapted to accommodate only limited forward movement of the rear axle, the angle through which the rear section of such a chassis can be moved is limited unless a special slip joint is incorporated at substantial expense into the main shaft. It would, of course, also be possible to avoid this problem by rearwardly extending the deck but this would again present weight distribution problems and difficulty in driving the vehicle. It has also been proposed to avoid this problem by providing such a modified vehicle effectively with a rearwardly extendable deck so that, before moving the deck into its inclined position, controls are operated to extend that deck rearwardly. This prior solution, however, presents several serious disadvantages. In the first place, such a sliding deck is inevitably quite expensive. Secondly, it presents the problem that, unless constructed in a very rugged and consequently highly expensive manner, it will be easily damaged during use, particularly if a heavy load is hauled onto the deck in a direction angularly disposed with respect to the longitudinal forward-rearward direction.
It is a principal object of this invention to provide a vehicle, such as a trailer but especially a truck, in which the disadvantage of the known and previously proposed structures for tilting deck vehicles are avoided or at least very substantially reduced.
Another object of this invention is to provide a vehicle of the type in question and which can be constructed by modification of an existing fixed deck vehicle at relatively low cost.
Yet another object of this invention is to provide a vehicle of the aforesaid type and which vehicle has a deck which is tilted through a relatively small angle while not extending an excessive distance rearwardly from its rear wheels so avoiding the weight distribution and drivability problem of many known and previously proposed vehicles.
A further object of this invention in accordance with a preferred feature thereof is to provide a tilting deck truck which can be manufactured by modification of an existing fixed deck truck without requiring the installation of a specially made slip joint in the main drive shaft of such a truck.
One more object of this invention in accordance with another preferred feature thereof is to provide a tilting deck vehicle incorporating safety features which will significantly reduce the risk of damage to the vehicle and injury to the driver thereof in the event of failure of the pivot means provided on such a vehicle.
Yet a further object of this invention is to provide a tilting deck vehicle which is not readily damaged even when heavy loads are hauled onto the deck of such a vehicle in a direction angularly disposed with respect to the forward-rearward direction.
Other objects of the invention will become apparent as the description herein proceeds.